Colorado Oil and Gas Operations Emit Far More Pollutants Than Expected

Winter air pollution in Denver, on Colorado's front range

Winter air pollution in Denver, on Colorado’s front range

Scientists affiliated with the National Oceanic and Atmospheric Administration (NOAA) have determined that oil and gas operations on Colorado’s front range are pumping almost three times more methane and seven times more benzene into the air than previously believed.

Benzene is a regulated air toxic that causes cancer, and methane is a potent greenhouse gas that is about 20-25 times more effective than carbon dioxide at trapping heat in Earth’s atmosphere.

For the study, researchers collected air samples from an airplane over two days in May, 2012. Prior studies measured air samples at ground-level, or from a 985-foot tall tower. This is the first study to measure airborne contaminants from an airplane.

Researchers found that the 24,000 active oil and gas wells that were operating in Weld County in May, 2012 were emitting a total of 19.3 tons of methane each hour, or about triple the amount the U.S. Environmental Protection Agency estimated would come from industry-reported emissions. The wells emitted benzene at a rate of 380 pounds each hour, or about eight times more than the 50 pounds an hour the Colorado Department of Public Health and Environment had estimated based on industry-reported data.

Colorado House Rep. Ray Scott (R-Grand Junction) promotes methane gas as an "incredibly clean fossil fuel" that "reduces emissions."

Colorado House Rep. Ray Scott (R-Grand Junction) erroneously promotes methane gas as an “incredibly clean fossil fuel” that “reduces emissions.”

Researchers were able to chemically “fingerprint” emissions coming from oil and gas operations, so they could isolate drilling operations as the specific source of the emissions they measured. They also found that oil and gas operations accounted for 75 percent of all the methane emissions in the area.

The new study confirms findings of a previous air quality study on data collected from ground sources in 2008, which also found oil and gas emissions were far higher than expected. At that time, Weld County had only 14,000 active wells. That study also found that sources other than wells, like storage tanks, pipelines and compressors, vented or leaked about 4 percent of their methane into the air — about twice the 2 percent loss rate the industry had calculated from their own data.

The new study also makes it clear that the idea that “natural gas” is a clean fuel is a myth.

Source: A new look at methane and non-methane hydrocarbon emissions from oil and natural gas operations in the Colorado Denver-Julesburg Basin, Journal of Geophysical Research, Manuscript accepted for publication on may 7, 2014

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